The present invention relates generally to methods and devices for handling semiconductor source material and more particularly to a method and apparatus for configuring and transporting a bulk container of source material.
The most common production technique for making semiconductor material is the Czochralski method in which high purity source material is melted down in a crucible within a crystal puller to form a melt. It is often desirable not to place all of the solid source material needed to form the melt in the crucible at one time. Some solid source material is preferably introduced to the crucible after melting has already commenced. Typically, the additional solid source material is pelletized polysilicon (often referred to in the industry as "Lite Poly") which is fed from a hopper connected to the crystal puller. The hopper may be occasionally supplied with source material which is received at the crystal puller facility in bulk containers. Supplying the hopper with source material is difficult for several reasons. The bulk containers are very heavy (approximately 275 kilograms), so that the containers are not easily transported nor easily inverted for gravity feed of the source material. Dispensing the source material from the container produces dust which is undesirable because the dust is easily contaminated. Further, if the dust is transferred to the melt, it can cause voids in the semiconductor material. Preferably, the dust is not introduced to the hopper. Moreover, exposure of the source material to the environment should be limited because of the risk of contaminating the source material. Presently, the hopper is supplied by decanting the source material from the bulk container into smaller containers, then transferring the smaller containers to the crystal puller and pouring the source material into the hopper. Often this procedure introduces dust into the hopper and exposes the source material to the environment.